1. Field of the Invention
The present invention relates to a display device, a computer terminal, and an antenna which are capable of wireless data communication.
2. Discussion of the Prior Art
Typically, a wired cable is used by a laptop to communicate with another processing device such as another laptop, desktop, server, or printer. To communicate without a wired connection, an antenna is needed. FIG. 1 shows two possibilities of outside antennas.
Antennas can be located at the top of a laptop display 1 for better RF clearance, or just outside (dash line for antenna) of a PCMCIA card 2. Usually, the laptop will have an optimum wireless performance if the antenna is mounted on the top of the display 1. However, an external antenna will generally be more expensive and susceptible to damage than an internal antenna. Alternatively, an internal or embedded antenna generally will not perform as well as an external antenna.
The commonly used method to improve the performance of an embedded antenna is to keep the antenna away from any metal component of the laptop. Depending on the design of the laptop and the type of antenna, the distance between the antenna and metal components could be at least 10 mm.
FIG. 2 shows some possible embedded antenna implementations. Two antennas are typically used, though applications implementing one antenna are possible. In one case, the two antennas are placed on the left 3 and right 4 edge of the display. Using two antennas instead of one antenna will reduce the blockage caused by the display in some directions and provide space diversity to the communication system. As a result, the size of the laptop becomes larger to accommodate antenna placement. In another configuration, one antenna can be placed on one side (3 or 4) of the display and a second antenna on the top 5 of the display. This latter antenna configuration may also provide antenna polarization diversity depending on the antenna design used.
For a computer terminal shown in FIG. 2B, since the antenna 1 is of a folding type, some time and labor will be needed for making the antenna 1 upright or folded and in addition, some moving parts may be damaged or the antenna may interfere with using the keyboard 6. Moreover, since the antenna 1 is attached to the base unit 7, the antenna location may be too low to achieve good receiving conditions.
For the computer terminal shown in FIG. 15, there may be another problem, since the antenna 157 is built in the housing 6 and it is located in its highest position when it is used. However, when the sleeve dipole antenna 157 is built in the housing 156, the housing 156 may become larger and display panel 155 smaller. This may be because the frame forming the outer portion of the display panel 155 is made of conductive metal and radio signals may be absorbed by the frame, thus the receiving capability of the antenna 157 may be degraded if the antenna 157 is not sufficiently distant from the frame. For example, when radio signals within a 2.5 GHz band are received, the antenna 157 of sleeve dipole type must be at a distance of approximately 30 mm from the outer portion of the display panel 155. In this way, when the antenna 157 is located at a distance from the outer portion of the display panel 155, the housing 156 will bulge in the lateral direction or the display panel 155 must be smaller if such bulging of the housing 156 is undesirable.
Particularly, a computer terminal may have a large display panel with an overall size unchanged or reduced and thus, as shown in FIG. 2C, spaces C1 and C2 between a display panel 8 and a housing 7 tend to be smaller and this tendency may go against the above-mentioned problems.
In addition, recently, the display housing 9 may be made of carbon fiberglass reinforced plastics (CFRP) or other suitable material for weight reduction. However, when the display housing 9 is made of CFRP, the antenna cannot receive radio signals through the display housing 9 on its backside but receive radio signals through the display panel 8 on its front side only, since CFRP is conductive material.
As wireless communications among processing devices become increasingly popular, a need exists for a compact integrated antenna having reduced costs and reliable performance.